This invention relates to directional coupling circuits, suitable for use at microwave frequencies, and more particularly to improvements therein.
One of the concerns of all directional couplers, toward the solution of which a great deal of effort has been made, is the issue of "ripple bandwidth." This is a figure of merit which is used to measure the uniformity of transmission across the operative bandwidth of the coupler. Obviously it is desirable to have signals at all of the frequencies within the bandwidth for which the coupler is to be used, passed therethrough without variation. However, the ideal situation has not been achieved thus far.